Are all your 4 sessions the same layout, but with different loading or do you switch the exercise order around and use different movements?
That sessions looks good, I’d probably just do the 1 set of squats as you’re doing an extension as well, if I’d add anything it would be a glute movement.
All sessions are same layout but on the heavy lower days I start with the lower body work first, then on the heavy upper days I start with the upper work. All 4 rotations use completely different exercises